It’s late June, and San Miguel Island’s white sand beaches are filled with barking sea lions. More than 100,000 of them. The marine mammals have come to this windy, remote island to breed and give birth – a rowdy, stinky summer extravaganza that last year, enigmatically, ended in disaster.

When the sea lions converged on this most westerly of southern California’s Channel Islands in May 2012, as they do every spring, there was no hint of anything amiss. A year later, thousands of pups – perhaps as many as 70 percent of the newborns – were dead. The struggle to survive led desperate pups from their sandy nursery into the churning, dangerous sea, long before they were ready.

Between January and June, five rescue centers along the southern California coast, from Santa Barbara to San Diego, took in more than 1,500 stranded pups – five times more than normal.